Actually, the record is correct but not for the city's main weather station. The temperature of 49C was recorded in two of the city's outer areas one of which was Najafgarh and other was Mungeshpur.
You can select those from the left nav on IMD's website and see the results yourself.
I live in a suburb of Delhi and to be honest it is not just the occasional days that it stays that high.
This year it has consistently been above 40C since late March. Summer has just started and the hottest months are generally May and June. So, it is going stay like this for more than three months this year in all.
Even worse is that unlike desert regions, even the night temperatures here stay above 30C many times during this part of the year. Sometimes you open the window at night expecting it to be better only to realize that a hot "breeze" is blowing.
Owing to the pandemic, I had spent the last couple of years in the foothills of the Himalaya where the temperature rarely went beyond 30C. It has been really hard coping up with the heat as it literally sucks the life out of you.
I have started writing a blog[1] about my treks in the Indian Himalayas. My pace of writing is really slow, so don't have too many articles in there yet. But have a couple of more posts in the pipeline.
I couldn't find the effectiveness of Covishield against Delta but for Covaxin the claimed efficacy is in the same ballpark at 65%. So this is not bad at all.